1. Field of the Invention
This invention relates to dental appliances and more particularly to orthodontic face bows.
2. Prior Art
The most pertinent prior art is my U.S. Pat. No. 4,212,637, issued July 5, 1980 and entitled ORTHODONTIC FACE BOW. In that patent other prior art, particularly the patents issued to S. J. Kloehn are recited. As pointed out in my earlier patent, the Kloehn face bow and related dental appliances utilize a inner bow which is either welded to or otherwise affixed to the outer bow in a non-separable fashion. As a result, if a child grabs the outer bow of the appliance worn by his friend and pulls the outer bow forward to such an extent that the free ends of the inner bow of the device are completely removed from the mouth there is a distinct possibility that when the outer bow is released the elastic band which holds the entire appliance on the head will cause the pointed ends of the inner bow to strike the eye or eyes of the wearer of the bow and blindness can and has occurred.
In my earlier patent, I described and claimed an orthodontic face bow which included an externally applied outer bow and an internally applied inner bow which were mechanically coupled to each other but which were mechanically separable from each other in the event the outer bow was pulled. In one version a pair of pins which were welded to the inner bow were received by a pair of tubular sleeves supported from the outer bow in a position to receive and properly orient the inner bow. While this structure has represented a significant advance in the orthodontic face bow art, it is possible for the direction of the pulling to be such as to cause the pins to drag within the sleeves so that the separation does not occur when it should and, as a consequence, damage may occur.
Therefore, it is an object of this invention to overcome the disadvantages of the prior art devices.
It is a further object of this invention to provide a separable inner and outer bow structure for an orthodontic face bow in which separation of the inner and outer bows at a predetermined force level can be positively assured.